Astronaut Riding Horse in Space

Create a square, painterly surreal oil painting of {argument name="main subject" default="an astronaut riding a horse through outer space"}. The astronaut wears a bulky white EVA spacesuit with a large backpack life-support unit, glossy black gold-tinted helmet visor, small red and blue suit markings, thick gloves and boots, seated upright in a brown leather saddle and holding red-brown reins. The horse is {argument name="horse color" default="chestnut brown with a white blaze and white lower legs"}, shown in a dynamic mid-gallop pose facing right, with wind-swept mane and tail, raised front legs, detailed bridle, and expressive realistic head. The setting is a deep navy-black cosmic background filled with swirling brushstrokes, tiny stars, faint nebulas, and exactly two large ringed planets: one colorful planet in the upper left with blue rings and yellow-green landlike shapes, and one bluish-purple ringed planet in the upper right. Use an expressive traditional oil-on-canvas look with visible thick brush texture, dramatic soft highlights, whimsical retro sci-fi fantasy mood, rich blues and browns, and no text or watermark.